Easy on energy

Equipment manufacturers are offering solutions such as LED lighting and distributed refrigeration systems to keep a cap on costs. By Kim Ann Zimmermann Supermarkets spend a lot to keep the food and customers at the right temperature. While energy costs have evened out a bit recently, supermarkets are not letting down their guard when it comes to monitoring how much is spent on refrigeration, lighting and other systems that suck up the juice—and not the bottled kind. “We see some significant trends among retailers relating to their concerns about environment and concerns about energy efficiency,” says Kurt Knapke, director, end-user sales, OEM refrigeration, for St. Louis-based Emerson Climate Technologies. He says one of the most significant changes over the past few years in terms of refrigeration has been the move from large centralized systems in the back room to systems that are dispersed throughout the store. “Many larger supermarkets are going to distributed or secondary loop refrigeration systems and both are enabling them to reduce refrigeration charge and improve efficiency,” Knapke says. “Five years ago, 80% of refrigeration systems were large racks, and roughly 5% were secondary loop and 15% were distributed systems. Today, it is about 50% large racks, 20% secondary loop and 30% distributed and we expect the trend away from large rack systems to continue.” Compressors are a key to improving the energy efficiency of refrigeration systems and Knapke points to several innovations such as the ability to adjust the capacity of the compressors from 10% to 100% depending on the time of the day, climate and other factors. In addition, he says Emerson’s Copeland Scroll compressor with vapor injection, provides a 50% increase in capacity and 20% increase in efficiency for grocers when combined with subcooling. One challenge facing every supermarket is keeping the frozen food and chilled aisles at the right temperature. The constant opening and closing of doors is good for sales but tough on heating and cooling costs. One solution being used at a number of supermarkets is the Air Pear Thermal Equalizer by Airius LLC, based in Longmont, Colo. “Customers tend to do a ‘grab and dash’ in the chilled and frozen food aisles, especially in the summer,” says Duke DiPane, Airius’ marketing coordinator. Unlike a paddle fan, he says the Air Pear uses a low-wattage, energy-efficient motor to drive a near-silent fan that aerodynamically and quietly forces a narrow column of hotter air from the ceiling directly to the cooler floor below, without blowing cold air from the coolers. Comfortable temps The Air Pear mixes the cooler air near the floor with warmer air from the ceiling. This equalizes the temperature of the air and floor where people live and work, he explains. The savings for the supermarket comes from not having to reheat cold air entering the makeup air system. “The makeup air system works a whole lot less and the temperature of the store is equalized, HVAC systems operate less and maintenance is reduced,” he says. The equipment is hung close to the ceiling and the Model 25 covers about 1,200 square feet, according to DiPane. “Currently, most of our supermarket users are targeting specific areas, such as the cold and frozen food aisles, but it can be used in any area of the store that can benefit from destratfication, such as the deli or café.” When it comes to keeping a lid on HVAC and refrigeration costs, retailers are literally doing just that by putting doors on refrigerated cases. Supermarkets can realize significant annual energy savings by switching from open multi-decks to door cases for medium-temperature products such as dairy, packaged deli meats, bagged produce, beer, premium juices and other beverages, according Carl Petersen, marketing and advertising manager for Zero Zone, based in North Prairie, Wis. “With our newest medium temp door case, the Crystal Merchandiser, for instance, we have identified energy reductions as high as 84%,” he says. “Transitioning to energy-efficient door cases works very well for store remodels, but provides even greater benefits for new store construction, lowering load requirements on the refrigeration rack, decreasing size and cost of rack equipment and even shortening the length of the rack itself.” Keeping up with maintenance In the case of remodels, Peterson adds that it is common for users of the Crystal Merchandiser be able to turn off some of the compressors on existing refrigeration racks, saving thousands on annual energy costs while also reducing refrigerant in the system. Bruce Hierlmeier, Zero Zone’s engineering manager, says that regular scheduled maintenance is critical for racks and display cases to pinpoint problems before they spiral out of control. “Com­puter­ized control systems and data loggers provide an operating history which helps the technician maintain the refrigeration system,” he says. Valves and controller settings should be verified periodically to make sure the system is operating as designed and case temperatures should be maintained at the highest temperature that results in safe food temperatures to minimize the amount of energy used by the refrigeration system, he says. He adds that regular leak inspection is especially important, since system leaks not only make the rack run less efficiently, but also to prevent catastrophic refrigerant leaks that are bad for the ozone layer and costly to remedy. “Regular inspection of compressors, valves and other system and case components is equally valuable in order to avoid potential problems before they pull down energy efficiency.” Because they do not generate heat and thrive in a cold environment, LED lights have been taking over for flourescents in freezers and refrigerated cases. “LEDs love the cold, which makes them a perfect solution for refrigerated and freezer cases,” says Karen Lee, head of applications marketing for Osram Sylvania, based in Danvers, Mass. “In addition, they come to full brightness instantly, so they can be put on a sensor so that the lights can be off when there are no customers in the aisles and switch on when there are shoppers.” Cool lights Bryan Warner, vice president of Largo, Fla.-based ElectraLED says that since LEDs don’t generate heat, the result is that the freezer case is less expensive to run. “There is a significant impact on cooling costs when retailers switch to LEDs, because every watt of lighting removed means that the compressor runs that much less. If you remove 300 watts of lighting from the freezer case, it is almost as if you are running it for free.” Beyond the freezer and refrigerated cases, LED lighting is gaining ground as an energy-saving lighting alternative in many areas of the supermarket.“There is an LED lighting solution for almost any application inside or outside of a retail facility,” says Bryan Beatenbough, president of EfficientLights, a division of PowerSecure, based in Anderson, S.C. “LEDs are now brighter and they offer a better color selection.” Areas such as parking lots, walk-in freezers and back rooms are prime targets for efficient lighting, according to Lee. “When you think of LEDs in the grocery environment, you typically think of the selling area. However, there are areas that have low occupancy such as the walk-in freezer in the back room where there is the potential to save money on lighting.”